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dragonfly: Fix legendre symbol calculation failure handling

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In case of low-memory conditions, the computation for legendre symbol
can fail and return -2 as per documentation, but the check for that
was missed here. And this can can cause an infinite loop searching for
qr and qnr if the error repeats for each attempt.

Break the loop if calculation fails, we can leave retry to the callers
or user. This is similar to the way allocation and generation of a new
random number was handled in this loop.

Signed-off-by: Chaitanya Tata <Chaitanya.Tata@nordicsemi.no>
This commit is contained in:
Chaitanya Tata 2023-11-06 22:49:15 +05:30 committed by Jouni Malinen
parent 76ae985b0a
commit 3e1fb2dec7
1 changed files with 6 additions and 3 deletions
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9
src/common/dragonfly.c
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@ -67,12 +67,15 @@ int dragonfly_get_random_qr_qnr(const struct crypto_bignum *prime,
}
res = crypto_bignum_legendre(tmp, prime);
if (res == 1 && !(*qr))
if (res == 1 && !(*qr)) {
*qr = tmp;
else if (res == -1 && !(*qnr))
} else if (res == -1 && !(*qnr)) {
*qnr = tmp;
else
} else {
crypto_bignum_deinit(tmp, 0);
if (res == -2)
break;
}
}
if (*qr && *qnr)